Cold cathode field emission devices (FEDs) are known in the art. FEDs have two or more electrodes, including an emitter and a collector. In addition, one or more gates may be provided to modulate operation of the device.
FEDs having substantially non-planar oriented electrodes are also known. In one prior art embodiment, the emitter constitutes a cone shaped object. Both a substantially normal vapor deposition process and a low angle vapor deposition process are used (typically simultaneously) to form the cone. The substantially normal vapor deposition process provides material to support construction of the emitter cone, and the low angle vapor deposition process provides for continual closing of an aperture that increasingly restricts introduction of material from the normal deposition process, thereby allowing gradual construction of the cone.
The above process gives rise to a number of problems. For example, the substrate upon which the FEDs are formed must be continually rotated during the low angle vapor deposition process in order to assure symmetrical closing of the aperture. In the absence of such symmetrical closing, the resultant emitter cone may be misshapen and likely ineffective to support its intended purpose. As another example, the normal and low angle vapor deposition processes typically occur simultaneously. Since the two processes typically result in deposition of differing materials, the resultant occluding layer (which is comprised of a mixture of materials) must almost always be removed in order to allow provision of a functional device.
Accordingly, a need exists for a method of forming substantially non-planar FEDs that substantially avoids at least some of these problems.